This invention relates generally to a rotary engine adapted for use in automobiles, and more particularly to the type of rotary engine featuring an improvement in the mixture suction mechanism which permits good stratification of the mixture in the combustion chamber.
In rotary engines known heretofore, the spark plugs are provided in sequestered recessed in the inner peripheral surface of the rotor housing, so that scavenging in the plugs becomes imperfect, resulting in a drawback in that a lean mixture is hard to ignite.
Also, in such rotary engines, although the flame produced by the spark plugs propagates at extremely high speed toward the leading side, or in the direction of rotation of the rotor, such flame propagation is sluggish on the trailing side, or in the direction opposite to the direction of rotor rotation, and this causes imperfect combustion on the trailing side, resulting in increased fuel consumption and increased discharge of unburned harmful components in the exhaust gas.
In order to overcome such defects of rotary engines, efforts have been extended for materializing a so-called stratified combustion system in which the mixture in the combustion chamber is stratified such that the mixture on the leading side is rich while that on the trailing side is lean. There have been proposed several methods for attaining such stratification of the mixture. In one such method, a rich mixture is first supplied, from a peripheral port upon passage of an apex seal through such port and then, with a slight delay, lean mixture or air is supplied from a side port with passage of a side seal therethrough. In another method, rich mixture is supplied together with lean mixture of air from the respective peripheral ports with passage of the respective apex seal therethrough.
However, according to the former method, since lean mixture or air is supplied from a direction substantially perpendicular to the high speed gas flow moving in the direction of rotation of the rotor in the combustion chamber, turbulence tends to occur in the flow of charge in the combustion chamber thereby making it difficult to accomplish definite stratification of the mixture.
In the latter method, no such problem of turbulence of the charge flow in the combustion chamber arises, but according to this latter method, it becomes essential that a peripheral port for feeding rich mixture and another peripheral port for feeding lean mixture or air are located at pertinent positions closely adjacent to each other. This requirement arises in consideration of the fact that the overlap of the charge and discharge is increased if the ports are positioned too close to the minor axis side while the effective compression ratio at low speed is reduced if the ports are positioned too distant from said minor axis side. However, it becomes hardly possible to aptly adjust the timing of port openings with passage of the apex seal and hence it is difficult to obtain a good pattern of stratification.
The present invention then aims at accomplishing good stratification of the mixture in the combustion chamber by overcoming the difficulties previously discussed. According to the present invention, both rich mixture and lean mixture or air are supplied from the respective peripheral ports at good timing relative to each other by means of rotary valves in the suction system with no regard to passage of the apex seals.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.